1. Field of the Invention
The invention relates to the preparation of dibenzocycloheptene and its derivatives.
2. Description of the Prior Art
The class of compounds having the structure ##STR2## possesses valuable physiological characteristics. Among these are antidepressant, analgesic, and anticonvulsive properties.
Compound A and its derivatives are presently prepared via multistep, multistage synthesis which involves ring closure of double-ring compounds. U.S. Pat. No. 3,409,640 presents such a method. The final stage of this process involves the ring closure of double-ring structures, for example, ##STR3## (2-phenylethylbenzoic acid). Such compounds are often expensive and/or not readily available. Therefore, it is necessary to prepare the double-ring compounds suitable for the above ring closure step. This additional preparation is time consuming and complex. In fact, as many as five steps may be added to the process because of the preparation of these double-ring compounds. (cf U.S. Pat. No. 3,409,640, col. 6, 1. 38, through col. 8, 1. 30).
The process presented by U.S. Pat. No. 3,409,640 is typical of the processes currently known to produce compound A and its derivatives in that such processes often involve reactants and compounds that are expensive or not readily available and/or involve numerous or complex preparative steps.
Compound A and its derivatives may also be prepared from anthracene and its derivatives as disclosed in Annales de Chimie (Paris) 6, 1445-1502 (1961) by dehydration of, e.g., 9,10-bis(hydroxymethyl)-9,10-dihydroanthracene. The alcohol is prepared by reduction with LiAlH.sub.4 of the methyl ester of 9,10-dihydroanthracene-9-carboxylic acid, which in turn is separated and purified in less than 30% yield from a mixture containing other acids, e.g., 9,10-dihydroanthracene-9,10-dicarboxylic acid. The mixture of acids is the product of CO.sub.2 reaction with sodium anthracide. Again, numerous preparative steps are required, and low yields of product are obtained.